Identification of rivers with high and good habitat quality: methodological approach and applications in Austria

摘要: The investigation of the 52 largest Austrian rivers with catchment areas >500 km2 (Danube River excluded) provides a national estimate ecological status Austria’s and an example current European alpine rivers. Emphasis is placed on evaluation criteria, such as morphological character, instream structures, longitudinal river corridor, lateral connectivity hydrological regime compared original conditions. This assessment nearly 5000 kilometers identifies remaining stretches high habitat quality well those that have been altered by systematic channelisation or hydropower development. Altogether, about 80% (3900 km) in ‘larger’ are moderately to heavily impacted human activity thus no longer correspond their channel form dynamics. Impoundment, water diversion hydropeaking each impact hydrology approximately 20% above stretches. Only all investigated can still be classified having good retaining essentially natural functions. Using conditions reference, most severe losses occurred reaches were originally braided meandering. Analysing amount unaltered according biocoenotic regions, 37% (523 rhithral (trout) region (1416 18% (480 hyporhithral (grayling) (2739 remain today quality. few intact (totaling 43 found along formerly potamal (731 km). These data underline rarity and, therefore, importance unspoiled aquatic habitats. results presented here basis for resource management nature conservation strategies, restoration programs. In particular, these investigations help fulfill requirements EU-Water Framework Directive assisting delineate characterise reference sites different types.